1. Field of Invention
The invention relates to electrolytic cells, particularly high amperage diaphragm electrolytic cells. The cells, typically chlor-alkali diaphragm cells, may operate at current capacities of upwards of about 200,000 amperes.
2. Description of the Related Art
It has been known to construct such cells where cathode outer sidewalls, made of electrically conductive material, are encircled with buss structure. For example, there has been shown in U.S. Pat. No. 3,390,072, a high amperage electrolytic cell wherein the sidewall is connected to a source of electrical current through an encircling bar-type bus member, sometimes referred to as a gird bar.
There has thereafter been developed busbar assemblies for diaphragm-type electrolytic cells wherein busbars are connected only to the cathode sidewall and have angled edges. For example, in U.S. Pat. No. 3,783,122, there are shown busbars of triangular shape, which busbars are shorter than the sidewall. Further in the development of angled busbars, several busbar strips, some of which can have triangular-shaped faces, may be utilized. This has been shown in U.S. Pat. No. 3,904,504, wherein it is disclosed to have a cathode busbar structure comprising several busbar strips. The numerous busbar strips, having different relative dimension, are welded to the sidewall.
With regard to fastening busbars to the sidewall, a combination of fastening means may be utilized. Generally, welding can provide for desirable electrical contact between the sidewall and a busbar. However, it is known to bolt a busbar to the sidewall, then weld the busbar at its edges to the sidewall. Bolting can assist in positioning of the busbar on the sidewall, then welding can assure desirable electrical contact as well as assisting in maintaining busbar positioning.
A more recent innovation for providing electrical current to electrolytic cells has improved the gird bar structure for distributing electrical current to the cathode sidewall. Thus as shown in U.S. Pat. No. 4,834,859, a gird bar is provided on a sidewall. In the structure of the innovation of this patent, distributor bars are placed on the inside of the sidewall at the upper and lower regions of the gird bar. These distributor bars conduct electrical current from the sidewall to an exterior face of an inner tube sheet. Cathode tubes are then positioned at the interior face of the tube sheet.
More recently, it has been proposed to provide a wall-sized busbar for the cathode sidewall. Such a structure is shown in U.S. Pat. No. 5,137,612. This patent discloses such a wall-sized busbar and the busbar is interface bonded to the cathode sidewall. The wall-sized busbar can have an extension section for attaching jumper switches.
It would nevertheless be desirable to provide a busbar structure for a cathode sidewall having not only efficient current distribution, but also reduced potential for sidewall stress corrosion cracking. It would also be desirable if such structure could provide reduced cathode manufacturing cost as well as accommodate stress relief characteristic.